I want to draw several plt charts with python script nodes and make them into table rows.
But I don’t know how I can convert the plt charts to table row images.
Here is how I tried to do it.
But I get a type error. ValueError: Data type 'binary' in column 'image' is not supported in KNIME Python. Please use a different data type.
in the past I had the same question. I came a across that saving the images to a local folder in the python script and loading them afterwards was the best way.
What I did:
Use “extract context properties” and search for “context.workflow.temp.location”
pass this to the python node and use this as the folder to store the files
create proper filenames and write images in python node
pass image location via pandas dataframe to KNIME
use “string to Path” and “Path to URI” to prepare the usage of
“Read Images” to read the images you just created into a table
delete images from the folder with the last node "Delete Files/Folders (Table)
Hi @hhkim,
You can export images in the output table by adding a pillow Image object to the table. Try this:
import knime.scripting.io as knio
import matplotlib.pyplot as plt
from io import BytesIO
from PIL import Image
import pandas as pd
# Example data for plotting
x = [1, 2, 3, 4]
y = [10, 20, 25, 30]
# Create a simple line plot
fig, ax = plt.subplots()
ax.plot(x, y)
ax.set_title("Example Plot")
ax.set_xlabel("X axis")
ax.set_ylabel("Y axis")
# Save the plot to a BytesIO buffer in PNG format
buf = BytesIO()
plt.savefig(buf, format='png')
plt.close(fig)
buf.seek(0)
# --- IMPORTANT PART: wrap the image as a PIL.Image object ---
img = Image.open(buf)
# ------------------------------------------------------------
# Create a DataFrame with the image in a column
# The column must contain PIL.Image objects for KNIME to recognize them as images
df = pd.DataFrame({"Image (PIL)": [img]})
# Output the table to KNIME
knio.output_tables[0] = knio.Table.from_pandas(df)
